Method and apparatus for pacing during revascularization

ABSTRACT

A system for use during revascularization includes a catheter having an adjustable balloon for delivery a stent, one or more pacing electrodes for delivering one or more pacing pulses to a patient&#39;s heart, and a pacemaker configured to generate the one or more pacing pulses to be delivered to the heart via the one or more pacing electrodes. The one or more pacing pulses are delivered at a rate substantially higher than the patient&#39;s intrinsic heart rate without being synchronized to the patient&#39;s intrinsic cardiac contractions, and are delivered before, during, or after an ischemic event to prevent or reduce cardiac injury.

CLAIM OF PRIORITY

This application is a continuation of and claims the benefit of priorityunder 35 U.S.C. §120 to U.S. patent application Ser. No. 13/113,706,filed on May 23, 2011, which is a continuation of and claims the benefitof priority under 35 U.S.C. §120 to U.S. patent application Ser. No.11/113,828, filed on Apr. 25, 2005, now issued as U.S. Pat. No.7,962,208, which is hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

This document relates generally to cardiac pacing systems andparticularly to a system for delivering pacing pulses during arevascularization procedure.

BACKGROUND

The heart is the center of a person's circulatory system. It includes anelectro-mechanical system performing two major pumping functions. Theleft portions of the heart draw oxygenated blood from the lungs and pumpit to the organs of the body to provide the organs with their metabolicneeds for oxygen. The right portions of the heart draw deoxygenatedblood from the body organs and pump it to the lungs where the blood getsoxygenated. These pumping functions are resulted from contractions ofthe myocardium (cardiac muscles). In a normal heart, the sinoatrialnode, the heart's natural pacemaker, generates electrical impulses,called action potentials, that propagate through an electricalconduction system to various regions of the heart to excite themyocardial tissues of these regions. Coordinated delays in thepropagations of the action potentials in a normal electrical conductionsystem cause the various portions of the heart to contract in synchronyto result in efficient pumping functions. A blocked or otherwiseabnormal electrical conduction and/or deteriorated myocardial tissuecause dyssynchronous contraction of the heart, resulting in poorhemodynamic performance, including a diminished blood supply to theheart and the rest of the body. The condition where the heart fails topump enough blood to meet the body's metabolic needs is known as heartfailure.

Myocardial infarction (MI) is the necrosis of portions of the myocardialtissue resulted from cardiac ischemia, a condition in which themyocardium is deprived of adequate oxygen and metabolite removal due toan interruption in blood supply caused by an occlusion of a blood vesselsuch as a coronary artery. The necrotic tissue, known as infarctedtissue, loses the contractile properties of the normal, healthymyocardial tissue. Consequently, the overall contractility of themyocardium is weakened, resulting in an impaired hemodynamicperformance. Following an MI, cardiac remodeling starts with expansionof the region of infarcted tissue and progresses to a chronic, globalexpansion in the size and change in the shape of the entire leftventricle. The consequences include a further impaired hemodynamicperformance and a significantly increased risk of developing heartfailure.

When a blood vessel such as the coronary artery is partially orcompletely occluded, a revascularization procedure such as percutaneoustransluminal coronary angioplasty (PCTA) can be performed to reopen theoccluded blood vessel. However, the revascularization procedure itselfinvolves a temporary occlusion of the coronary artery. In addition,plaques dislodged and displaced by the revascularization procedure mayenter small blood vessels branching from the blood vessel in which therevascularization is performed, causing occlusion of these small bloodvessels. This complication is referred to as “snow plow effect.” Therevascularization procedure may also cause distal embolization, i.e.,obstruction of the artery caused by the plaque dislodged during theprocedure. The temporary occlusion, snow plow effect, and distalembolization may each cause cardiac injuries such as further expansionof the region of infarcted tissue. In addition, the revascularizationprocedure is known to increase the risk for occurrences of arrhythmia.

Therefore, there is a need for minimizing cardiac injury and preventingarrhythmias during the revascularization procedure.

SUMMARY

A system for use during revascularization includes a catheter having anadjustable balloon for delivery a stent and a pacemaker to deliver oneor more pacing pulses to a patient's heart to prevent or reduce cardiacinjury associated with the revascularization procedure. In oneembodiment, a system includes a catheter, one or more pacing electrodes,and a pacemaker. The catheter includes a proximal end portion, a distalend portion, and an elongate body extending therebetween. The distal endportion includes an adjustable balloon for delivering a stent. The oneor more pacing electrodes configured to deliver one or more pacingpulses to a heart of a patient. The pacemaker is configured to generatethe one or more pacing pulses to be delivered to the heart via the oneor more pacing electrodes. The one or more pacing pulses are deliveredat a rate substantially higher than the patient's intrinsic heart ratewithout being synchronized to the patient's intrinsic cardiaccontractions, and are delivered before, during, or after an ischemicevent to prevent or reduce cardiac injury.

In one embodiment, a method for delivering cardiac pacing to a patientis provided. A stent is delivered using a catheter including a stentdelivery system causing an ischemic event in a patient. The heart of thepatient is paced before, during, or after the ischemic event in a mannersuch that the pacing pulses are delivered at a rate substantially higherthan the patient's intrinsic heart rate without being synchronized tothe patient's intrinsic cardiac contractions.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects of the invention will be apparent to persons skilled in the artupon reading and understanding the following detailed description andviewing the drawings that form a part thereof. The scope of the presentinvention is defined by the appended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate generally, by way of example, variousembodiments discussed in the present document. The drawings are forillustrative purposes only and may not be to scale.

FIG. 1 is an illustration of an embodiment of a system providing forpacing during revascularization and portions of an environment in whichthe system is used.

FIG. 2 is an illustration of an embodiment of a pacemaker providing forpacing during revascularization.

FIG. 3 is a timing diagram illustrating an exemplary embodiment of acardiac protection pacing sequence for the pacing duringrevascularization.

FIG. 4 is an illustration of an embodiment of a PTVI device with pacingelectrodes.

FIG. 5 is an illustration of another embodiment of a PTVI device withpacing electrodes.

FIG. 6 is an illustration of another embodiment of a PTVI device withpacing electrodes.

FIG. 7 is an illustration of an exemplary specific embodiment of thedistal end portion of a PTVI device with pacing electrode(s).

FIG. 8 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

FIG. 9 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

FIG. 10 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

FIG. 11 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

FIG. 12 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

FIG. 13 is an illustration of another exemplary specific embodiment ofthe distal end portion of a PTVI device with pacing electrode(s).

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that the embodiments may be combined, or that otherembodiments may be utilized and that structural, logical and electricalchanges may be made without departing from the spirit and scope of thepresent invention. The following detailed description provides examples,and the scope of the present invention is defined by the appended claimsand their legal equivalents.

It should be noted that references to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.

This document discusses a pacing system for minimizing damage to themyocardial tissue and preventing arrhythmias during a revascularizationprocedure that requires temporary occlusion of one or more bloodvessels. In a specific application, this system provides for cardiacprotection pacing during a percutaneous transluminal coronaryangioplasty (PTCA) procedure. Cardiac protection pacing includes thedelivery of a pacing therapy before, during, and/or after the temporaryocclusion of a coronary artery associated with the PTCA procedure, forpreventing or reducing adverse effects of the occlusion, which is anischemic event. The pacing therapy can be delivered at almost any timeduring a revascularization procedure, as soon as pacing electrodes arein place, without substantially interfering with the revascularizationprocedure.

To deliver pacing pulses during a revascularization procedure, one ormore pacing electrodes are incorporated onto the distal end portion of aPTVI device. Examples of such PTVI device include guide wires,dilatation balloon catheters, stent delivery systems, brachytherapydevices, atherectomy devices, distal embolization protection devices,and guiding catheters. A pacemaker is connected to the proximal endportion of the PTVI device to deliver the pacing pulses to the heartthrough the one or more electrodes. In one embodiment, the pacemaker isan external pacing device such as a pacing system analyzer. Thisapproach to cardiac protection pacing allows delivery of pacing pulsesas soon as the PTVI device is inserted.

FIG. 1 is an illustration of an embodiment of a system 100 providing forpacing during revascularization and portions of an environment in whichsystem 100 is used. System 100 includes a PTVI device 110, a pacemaker130, and a cable 125 connecting PTVI device 110 and pacemaker 130. Whenneeded, system 100 also includes a reference electrode 122, which is asurface electrode, such as a skin patch electrode, connected to a lead120. Lead 120 is connected to a connector 118 allowing its connection tocable 125.

PTVI device 110 is used during a revascularization procedure andincludes a distal end portion 111 for intravascular placement and aproximal end portion 112. Proximal end portion 112 includes a proximalend device 114 and pacing connectors 116 and 117. Proximal end device114 includes various connectors and other structures allowingmanipulation of PTVI device 110 including the percutaneous transluminalinsertion of the device and operation of an angioplasty device at distalend 111. Pacing connectors 116 and 117 provide for electricalconnections between cable 125 and PTVI device 110. In one embodiment, asillustrated in FIG. 1, PTVI device 110 is a percutaneous transluminalcoronary angioplasty (PTCA) device used in a PTCA procedure. During thePTCA procedure, an opening 105 is made on a femoral artery 104 in apatient's body 102. PTVI device 110 is inserted into femoral artery 104and advanced to an aorta 106 and then to a right coronary artery 107,which is narrowed or blocked. The angioplasty device at distal end 111is then used to open up the blocked right coronary artery 107. Inanother embodiment, PTVI device 110 is used to open up a blocked leftcoronary artery 108.

Distal end portion 111 of PTVI device 110 includes one or more pacingelectrodes to allow pacing pulses to be delivered to a heart 101 duringthe PTCA procedure. In one embodiment, pacing pulses are deliveredthrough two pacing electrodes on distal end portion 111 of PTVI device110. In another embodiment, pacing pulses are delivered through a pacingelectrode on distal end portion 111 of PTVI device 110 and surfaceelectrode 122 functioning as the return electrode for pacing.

Pacemaker 130 delivers pacing pulses by following a cardiac protectionpacing sequence. In one embodiment, the cardiac protection pacingsequence provides for cardiac protection pacing following an ischemicevent to prevent arrhythmias and cardiac injuries caused by the ischemicevent. In one embodiment, pacemaker 130 is an external pacemaker such asa pacing system analyzer (PSA). In another embodiment, pacemaker 130includes an implantable pacemaker adapted for external use.

It is to be understood that FIG. 1 is for illustrative, but notrestrictive, purposes. For example, the physical structure of proximalend portion 112 depends on functional and ease-of-use considerations.Proximal end device 114 represents a structure that accommodates all themechanical connection and access requirements, which depend on thespecific configuration and function of PTVI device 110. In oneembodiment, proximal end device 114 includes an integrated device asillustrated in FIG. 1. In another embodiment, proximal end device 114branches out into multiple connectors and/or other devices. Pacingconnectors 116 and 117 represent a structure that accommodates all theelectrical connections required for delivering pacing pulses frompacemaker 130 to PTVI device 110. The number of pacing connectorsdepends on the number of pacing electrodes incorporated onto PTVI device110 and how it is to be connected to cable 125. In one embodiment, whenmore than one electrical connection is incorporated onto PTVI device110, proximal end portion 112 includes branched-out pacing connectorssuch as pacing connectors 116 and 117 as illustrated in FIG. 1. Inanother embodiment, proximal end portion 112 includes a single connectorproviding for multiple, independent electrical connections.

FIG. 2 is an illustration of an embodiment of a pacemaker 230 thatprovides for pacing during revascularization. Pacemaker 230 is aspecific embodiment of pacemaker 130 and includes a pacing outputcircuit 232 and a control circuit 234. In one embodiment, pacemaker 230further includes a user interface to allow a user to control thedelivery of the pacing pulses by controlling the pacing parametersand/or the timing of the delivery.

Pacing output circuit 232 delivers pacing pulses to PTVI device 110through cable 125. Control circuit 234 controls the delivery of thepacing pulses. In one embodiment, as illustrated in FIG. 2, controlcircuit 234 includes a cardiac protection pacing sequence timer 236,which times a predetermined cardiac protection pacing sequence. Thecardiac protection pacing sequence is predetermined to provide cardiacprotection pacing before, during, and/or after an ischemic event such asthe occlusion of a coronary artery by PTVI device 110 during a PTCAprocedure.

FIG. 3 is a timing diagram illustrating an exemplary embodiment of acardiac protection pacing sequence for pacing during a revascularizationprocedure such as a PTCA procedure. The cardiac protection pacingsequence is initiated after a time interval 340, which starts when theinsertion of PTVI device into body 102 is completed. Time interval 340expires before, during, and/or after an ischemic event that occurs whenthe blood vessel at the revascularization site is substantially occludedby PTVI device 110. In one embodiment, the cardiac protection pacingsequence is applied repeatedly, before, during, and/or after theischemic event, during the revascularization procedure.

In the embodiment illustrated in FIG. 3, the cardiac protection pacingsequence includes alternating pacing and non-pacing periods. Each pacingperiod is a pacing duration during which the pacing pulses are deliveredin a predetermined pacing mode. The non-pacing period is a non-pacingduration during which no pacing pulses is delivered. In one embodiment,during each pacing period, rapid, asynchronous pacing is applied. Inother words, pacing pulses are delivered at a rate substantially higherthan the patient's intrinsic heart rate without being synchronized tothe patient's intrinsic cardiac contractions. For illustrative purposeonly, FIG. 3 shows a cardiac protection pacing sequence that includestwo cycles of alternating pacing and non-pacing periods: pacing period342A, non-pacing periods 344A, pacing period 342B, and non-pacingperiods 344B. In one embodiment, the number of the cycles of alternatingpacing and non-pacing periods is programmable, and each of the pacingand non-pacing periods is programmable. In one embodiment, the cardiacprotection pacing sequence is initiated before the ischemic event andincludes approximately 1 to 4 cycles of alternating pacing andnon-pacing periods. The pacing period is in a range of approximately 30seconds to 20 minutes. The non-pacing period is in a range ofapproximately 30 seconds to 20 minutes. In a specific example, thecardiac protection pacing sequence initiated before the ischemic eventincludes 3 cycles of alternating pacing and non-pacing periods eachbeing approximately 5-minute long. In one embodiment, the cardiacprotection pacing sequence is initiated during the ischemic event andincludes approximately 1 to 4 cycles of alternating pacing andnon-pacing periods. The pacing period is in a range of approximately 30seconds to 20 minutes.

The non-pacing period is in a range of approximately 30 seconds to 20minutes. In a specific example, the cardiac protection pacing sequencedelivered during the ischemic event includes 3 cycles of alternatingpacing and non-pacing periods each being approximately 5-minute long. Inone embodiment, the cardiac protection pacing sequence is initiatedafter the ischemic event and includes approximately 1 to 4 cycles ofalternating pacing and non-pacing periods. The pacing period is in arange of approximately 10 seconds to one minute. The non-pacing periodis in a range of approximately 10 seconds to one minute. In one specificexample, the cardiac protection pacing sequence delivered after theischemic event includes 2 to 4 cycles of alternating pacing andnon-pacing periods each being approximately 30-second long.

In various other embodiments, the cardiac protection pacing sequenceincludes pacing at one or more atrial tracking or other pacing modes.Examples of pacing modes used in such a cardiac protection pacingsequence include VDD, VVI, and DDD modes. In various embodiments, theVVI and DDD modes are delivered with a lower rate limit higher than thepatient's intrinsic heart rate. In one embodiment, pacing therapy isdelivered to prevent restenosis. In another embodiment, pacing therapyis delivered to treat an arrhythmia during the revascularizationprocedure, for example, when the patient experiences bradycardia duringthe procedure.

In one embodiment, the pacing pulses are delivered according to thecardiac protection pacing sequence through PTVI device 110 during therevascularization procedure. After the revascularization procedure, ifan implantable pacemaker is implanted into the patient, pacing therapyis delivered to heart 101 through one or more implantable leads from theimplantable pacemaker. The pacing therapy includes delivering pacingpulses according to a pacing sequence that is substantially identical orsimilar to the cardiac protection pacing sequence applied during therevascularization procedure. The pacing sequence is delivered accordingto a predetermined schedule, such as on a predetermined periodic basis.This prevents or reduces possible cardiac injury after therevascularization, including cardiac injury and occurrences ofarrhythmia caused by ischemic events including myocardial infarctionthat may be experienced by the patient after the implantation of theimplantable pacemaker.

FIG. 4 is an illustration of an embodiment of a PTVI device 410. PTVIdevice 410 is a specific embodiment of PTVI device 110 and has anelongate body 450 between a distal end portion 451 and a proximal endportion 452. Distal end portion 451 is configured for intravascularplacement and includes a distal tip 453. Distal tip 453 includes apacing electrode 454. A conductor 456 extends longitudinally withinelongate body 450 and connected between pacing electrode 454 and aconnector 458, which is part of proximal end portion 452.

In one embodiment, elongate body 450 is an elongate cylindrical shafthaving a diameter in a range of approximately 0.2 mm to 1.5 mm, and PTVIdevice 410 has a length in a range of approximately 30 cm to 300 cm. Inanother embodiment, elongate body 450 is an elongate tubular body havingan outer diameter in a range of approximately 0.5 mm to 8 mm and aninner diameter (of a lumen) in a range of approximately 0.4 mm to 7 mm.In one embodiment, PTVI device 410 is a guide wire such as a coronaryguide wire. PTVI device 410 is formed by conductor 456, which isinsulated throughout its length except for pacing electrode 454 andconnector 458. As the core of the guide wire, conductor 456 is made of ametallic material such as stainless steel, alloys of nickel, titanium,and cobalt, and is insulated with a material such as silicone,polyurethane, Teflon, and polytetrafluoroethylene (PTFE). Electrode 454is made of a metallic material such as platinum, and iridium alloy. Inanother embodiment, conductor 456 is a metal wire other than the core ofthe guide wire. In another embodiment, PTVI device 410 is a guidingcatheter such as a coronary guiding catheter. The coronary guidingcatheter includes an elongate tubular body with a lumen extendingbetween distal end portion 452 and proximal end portion 452. In anotherembodiment, PTVI device 410 includes two or more electrodes in distalend portion 451 and two or more conductors each connected between one ofthe electrodes and connector 458, which is a multi-conductor connectorallowing for two or more electrically insulated connections.

FIG. 5 is an illustration of another embodiment of a PTVI device 510.PTVI device 510 is another specific embodiment of PTVI device 110 andhas an elongate body 550 between a distal end portion 551 and a proximalend portion 552. Distal end portion 551 is configured for intravascularplacement and includes a distal tip 553 and an angioplasty device 560.Angioplasty device 560 has one end approximately adjacent to distal tip553 and another end coupled to elongate body 550. In variousembodiments, angioplasty device 560 allows for application of anangioplasty therapy such as vascular dilatation, stent delivery,brachytherapy (radiotherapy), atherectomy, or embolic protection. In oneembodiment, angioplasty device 560 includes an adjustable portion thathas controllable expandability and contractibility. In one specificembodiment, angioplasty device 560 includes a balloon that is inflatedand deflated through a passageway longitudinally extending withinelongate body 550 and connected between the chamber of the balloon and aconnector at proximal end portion 552. The balloon is inflatable usingan air pump connected to that connector. In one embodiment, distal tip553 is a tapered tip that facilitates the insertion of PTVI device 510into a blood vessel. A pacing electrode 554A is approximately adjacentto one end of angioplasty device 560. Another pacing electrode 554B isapproximately adjacent to the other end of angioplasty device 560. Aconductor 556A extends longitudinally within elongate body 550 and isconnected between pacing electrode 554A and a pacing connector 516,which is part of proximal end portion 552. A conductor 556B extendslongitudinally within elongate body 550 and is connected between pacingelectrode 554B and a pacing connector 517, which is also part ofproximal end portion 552. In an alternative embodiment, pacingconnectors 516 and 517 are physically integrated into onemulti-conductor connector. Proximal end portion 552 also includes aproximal end device 514. Proximal end device 514 represents a structurethat accommodates all the mechanical connection and access requirements,which depend on the function of angioplasty device 560. In oneembodiment, proximal end device 514 includes an integrated device asillustrated in FIG. 5. In another embodiment, proximal end device 514branches out into multiple connectors and/or other devices.

In one embodiment, elongate body 550 is an elongate cylindrical shafthaving a diameter in a range of approximately 1 mm to 5 mm. PTVI device510 has a length in a range of approximately 50 cm to 150 cm. In oneembodiment, angioplasty device 560 has a fixed, substantiallycylindrical shape with a diameter in a range of approximately 1 mm to 10mm. In another embodiment, angioplasty device 560 has an adjustable,substantially cylindrical or semi-spherical shape with a maximumdiameter in a range of approximately 1 mm to 10 mm when fully expandedand a maximum diameter in a range of approximately 0.5 mm to 5 mm whenfully contracted. In one embodiment, PTVI device 510 is a PTCA catheterand includes a lumen longitudinally extending within elongate body 550to accommodate at least a portion of a guide wire such as PTVI device410. In one embodiment, conductors 556A and 556B are each made of ametallic material such as stainless steel and alloys of nickel,titanium, and cobalt. Electrodes 554A and 554B are each made of ametallic material such as platinum, and iridium alloy. Elongate body 550has a tubular outer shell made of a material such as silicone,polyurethane, Teflon, and polytetrafluoroethylene (PTFE).

In one alternative embodiment, PTVI device 510 includes one electrode indistal end portion 551 and one conductor connected between thatelectrode and a pacing connector in proximal end portion 552. In anotheralternative embodiment, PTVI device 510 includes three or moreelectrodes in distal end portion 551 and three or more conductors eachconnected between one of the electrodes a pacing connector in proximalend portion 552.

FIG. 6 is an illustration of another embodiment of a PTVI device 610with pacing electrodes. PTVI device 610 is another specific embodimentof PTVI device 110 and is similar to PTVI device 510 except for thelocation of the pacing electrodes. PTVI device 610 has a distal endportion 651, where pacing electrodes 654A and 654B are attached ontoangioplasty device 560. In one specific embodiment, pacing electrodes654A and 654B are each approximately adjacent to one end of angioplastydevice 560.

PTVI devices 410, 510, and 610 are illustrated in FIGS. 4-6 forillustrative but not restrictive purposes. For example, the one or morepacing electrodes can be distributed on the distal portion of a PTVIdevice in any way allowing proper delivery of pacing pulses. In variousembodiments, the one or more pacing electrodes can be distributed on theangioplasty device, the distal tip, and/or the elongate body at thedistal end portion of the PTVI device.

FIGS. 7-13 illustrate exemplary specific embodiments of the distal endof a PTVI device with one or more pacing electrodes. In one embodiment,PTVI device 410, 510, and 610 are each made by modifying a selectedproduct of Guidant Corporation's Vascular Intervention division(“Guidant VI,” Temecula, California) to include one or more pacingelectrodes. Examples of such a selected product are illustrated in FIGS.7-13. According to the present subject matter, one or more pacingelectrodes are incorporated onto any PTVI device as deemed appropriateby one skilled in the art. Such PTVI devices include, but are notlimited to, devices that belong to the same category as thoseillustrated in FIGS. 7-13.

FIG. 7 is an illustration of an embodiment of the distal end portion751, which is an exemplary specific embodiment of distal end portion451. Distal end portion 751 is the distal portion of a coronary guidewire (Guidant VI's HI-TORQUE PILOT™ 50 Guide Wire with Hydrocoathydrophilic coating) modified to include a pacing electrode 754. Thecoronary guide wire includes an elongate body 750 being an insulatedconductive wire that extends to a distal tip 753. The coronary guidewire has a length of approximately 190 cm or 300 cm, depending on thespecific product model, and a diameter of approximately 0.014 inches(0.3556 mm). The conductive wire is connected to pacing electrode 754 atthe distal end of distal tip 753. Distal end portion 751 also includes aradiopaque marker 762, which allows for measurement of lesion length. Inone embodiment, the single-electrode configuration allows the coronaryguide wire to have a relatively small diameter. In one embodiment,pacing pulses are delivered using a unipolar electrode configuration,with a return electrode such as reference electrode 122.

FIG. 8 is an illustration of an embodiment of the distal end portion851, which is an exemplary specific embodiment of distal end portion551. Distal end portion 851 is the distal portion of a coronarydilatation balloon catheter (Guidant VI's VOYAGER™ RX CoronaryDilatation Catheter) modified to include pacing electrodes 854A and854B. Distal end portion 851 is extended from an elongate body 850 andincludes a tapered tip 853 and an angioplasty device 860. The coronarydilatation balloon catheter has a usable catheter working length ofapproximately 143 cm and accommodates a guide wire having a maximumdiameter of 0.014 inches (0.3556 mm), such as the coronary guide wireillustrated in FIG. 7, that is used for insertion of the catheter.Elongate body 850 includes a shaft having a diameter in a range ofapproximately 2.0 to 2.8 French, depending on the specific productmodel. Angioplasty device 860 is a specific embodiment of angioplastydevice 560 and includes an adjustable balloon 864 that is approximatelyadjacent to tapered tip 853. Adjustable balloon 864 is used for coronarydilatation by inflation. When inflated, adjustable balloon 864 has adiameter in a range of 1.5 mm to 4 mm, depending on the specific productmodel. Pacing electrode 854A is approximately adjacent to one end ofadjustable balloon 864. Pacing electrode 854B is approximately adjacentto the other end of adjustable balloon 864. Pacing pulses are deliveredusing a bipolar configuration with pacing electrodes 854A and 854B, aunipolar configuration using one of pacing electrodes 854A and 854B anda return electrode such as reference electrode 122, or a combination ofbipolar and unipolar configurations.

FIG. 9 is an illustration of an embodiment of the distal end portion951, which is an exemplary specific embodiment of distal end portion551. Distal end portion 951 is the distal portion of a stent deliveryplatform (Guidant VI's GUIDANT MULTI-LINK RX ULTRA™ Coronary StentSystem) modified to include pacing electrodes 954A and 954B. Distal endportion 951 is extended from an elongate body 950 and includes a tip 953and an angioplasty device 960. The stent delivery platform accommodatesa guide wire having a maximum diameter of 0.014 inches (0.3556 mm), suchas the coronary guide wire illustrated in FIG. 7, that is used forinsertion of the device. Angioplasty device 960 is a specific embodimentof angioplasty device 560 and includes an adjustable balloon 964 that isapproximately adjacent to tip 953. Adjustable balloon 964 is used forplacing a stent in the coronary artery where distal end portion 951 hasreached. Depending on the specific product model, the working size ofadjustable balloon 964 accommodates stents having a diameter in a rangeof approximately 3.5 mm to 5mm and a length in a range of approximately13 mm to 38 mm. Pacing electrode 954A is approximately adjacent to oneend of adjustable balloon 964. Pacing electrode 954B is approximatelyadjacent to the other end of adjustable balloon 964. Distal end portion951 also includes a pair of radiopaque markers 962A and 962B onadjustable balloon 964 for indicating the balloon's working length.Pacing pulses are delivered using a bipolar configuration with pacingelectrodes 954A and 954B, a unipolar configuration using one of pacingelectrodes 954A and 954B and a return electrode such as referenceelectrode 122, or a combination of bipolar and unipolar configurations.

FIG. 10 is an illustration of an embodiment of the distal end portion1051, which is an exemplary specific embodiment of distal end portion551. Distal end portion 1051 is the distal portion of a brachytherapydevice (Guidant VI's GALILEO® Intravascular Radiotherapy System)modified to include pacing electrodes 1054A and 1054B. Distal endportion 1051 is extended from an elongate body 1050 and includes atapered tip 1053 and an angioplasty device 1060. The brachytherapydevice accommodates a guide wire having a maximum diameter of 0.014inches (0.3556 mm), such as the coronary guide wire illustrated in FIG.7, that is used for insertion of the device. Angioplasty device 1060 isa specific embodiment of angioplasty device 560 and includes anbrachytherapy device 1066 that is approximately adjacent to tapered tip1053 and includes a chamber containing an radiological agent to providetherapeutic doses to the tissue area where distal end portion 1051 hasreached. Brachytherapy device 1066 has diameter in a range ofapproximately 2.5 mm, 3.0 mm, or 3.5 mm and a therapeutic dose length ofapproximately 32 mm or 52 mm, depending on the specific product model.Pacing electrode 1054A is approximately adjacent to one end ofbrachytherapy device 1066. Pacing electrode 1054B is approximatelyadjacent to the other end of brachytherapy device 1066. Distal endportion 1051 also includes a pair of radiopaque markers 1062A and 1062Bon brachytherapy device 1066 for indicating the therapeutic dose length.Pacing pulses are delivered using a bipolar configuration with pacingelectrodes 1054A and 1054B, a unipolar configuration using one of pacingelectrodes 1054A and 1054B and a return electrode such as referenceelectrode 122, or a combination of bipolar and unipolar configurations.

FIG. 11 is an illustration of an embodiment of the distal end portion1151, which is an exemplary specific embodiment of distal end portion551. Distal end portion 1151 is the distal portion of an atherectomydevice (Guidant VI's FLEXI-CUT® Directional Debulking System) modifiedto include pacing electrodes 1154A and 1154B. Distal end portion 1151 isextended from an elongate body 1150 and includes a tapered tip 1153 andan angioplasty device 1160. The atherectomy device has a working lengthof approximately 134 cm. Angioplasty device 1160, which is a specificembodiment of angioplasty device 560, is an atherectomy device thatincludes a cylindrical nosecone 1168 that is approximately adjacent totapered tip 1153 and a cutter 1170 connected to cylindrical nosecone1168. Cutter 1170 cuts the plaques that block or narrow the portion ofthe coronary artery where distal end portion 1151 has reached.Cylindrical nosecone 1168 stores the cut plaques. Depending on thespecific product model, atherectomy device is capable of operating inblood vessels having diameters ranging from approximately 2.5 mm to 4mm. Pacing electrode 1154A is on tapered tip 1153 and approximatelyadjacent to the distal end of cylindrical nosecone 1168. Pacingelectrode 1154B is on cutter 1170 and approximately adjacent to thedistal end of cutter 1170. Pacing pulses are delivered using a bipolarconfiguration with pacing electrodes 1154A and 1154B, a unipolarconfiguration using one of pacing electrodes 1154A and 1154B and areturn electrode such as reference electrode 122, or a combination ofbipolar and unipolar configurations.

FIG. 12 is an illustration of an embodiment of the distal end portion1251, which is an exemplary specific embodiment of distal end portion551. Distal end portion 751 is the distal portion of a distalembolization protection device (Guidant VI's RX ACCUNET™ EmbolicProtection System) modified to include pacing electrodes 1254A and1254B. Distal end portion 1251 is extended from an elongate body 1250and includes a tip 1253 and an angioplasty device 1260. Elongate body1250 is based on a coronary guide wire that has a diameter of 0.014inches (0.3556 mm) and extends throughout substantially the full lengthof the distal embolization protection device, which is either 190 cm or300 cm, depending on the specific product model. Angioplasty device1260, which is a specific embodiment of angioplasty device 560, is anembolic protection device that includes a filter basket 1272 with afilter membrane 1274 to contain and remove embolic material includingplaques dislodged during the angioplasty procedure. Filter basket 1272is flexible, with available basket diameters (when fully expanded) of4.5 mm, 5.5 mm, 6.5 mm, and 7.5 mm, depending on the specific productmodel. Pacing electrode 1254A is on tip 1253. Pacing electrode 1254B ison elongate body 1250 and is approximately adjacent to the proximal endof filter basket 1272. Pacing pulses are delivered using a bipolarconfiguration with pacing electrodes 1254A and 1254B, a unipolarconfiguration using one of pacing electrodes 1254A and 1254B and areturn electrode such as reference electrode 122, or a combination ofbipolar and unipolar configurations.

FIG. 13 is an illustration of an embodiment of the distal end portion1351, which is another exemplary specific embodiment of distal endportion 451. Distal end portion 1351 is the distal portion of a coronaryguiding catheter (Guidant VI's VIKING OPTIMA™ 50 Guiding Catheter)modified to include a pacing electrode 1354. The coronary guidingcatheter includes a tubular elongate body 1350 that has a distal tip1353, and a lumen having a diameter of 6 French (0.068 inches), 7 French(0.078 inches), or 8 French (0.091 inches). In one embodiment, thesingle-electrode configuration allows the coronary guiding catheter tohave a relatively small diameter. In one embodiment, pacing pulses aredelivering using a unipolar electrode configuration, with a returnelectrode such as reference electrode 122.

It is to be understood that the above detailed description, includingthe various configurations of PTVI devices, is intended to beillustrative, and not restrictive. In general, cardiac protection pacingis applied to prevent or reduce cardiac injury and/or occurrences ofarrhythmia caused by an ischemic event by using one or more pacingelectrodes incorporated onto any intravascular device and a pacemakerthat is capable of delivering pacing pulses according to a predeterminedcardiac protection pacing sequence. Other embodiments will be apparentto those of skill in the art upon reading and understanding the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A system comprising: a catheter including aproximal end portion, a distal end portion, and an elongate bodyextending therebetween, wherein the distal end portion includes anadjustable balloon for delivering a stent; one or more pacing electrodesconfigured to deliver one or more pacing pulses to a heart of a patient;a pacemaker configured to generate the one or more pacing pulses to bedelivered to the heart via the one or more pacing electrodes, whereinthe one or more pacing pulses are delivered at a rate substantiallyhigher than the patient's intrinsic heart rate without beingsynchronized to the patient's intrinsic cardiac contractions and aredelivered before, during, or after an ischemic event to prevent orreduce cardiac injury.
 2. The system of claim 1 wherein the ischemicevent is the occlusion of the blood vessel in which the stent is to bedelivered.
 3. The system of claim 1 wherein the pacemaker is an externalpacemaker.
 4. The system of claim 1, wherein the control circuit isconfigured to cause the pacing pulses to be delivered at the ratesubstantially higher than the patient's intrinsic heart rate withoutbeing synchronized to the patient's intrinsic cardiac contractionsduring a pacing period programmable in a range of approximately 10seconds to 20 minutes.
 5. A method for delivering cardiac pacing to apatient, the method comprising: delivering a stent using a catheterincluding a stent delivery system causing an ischemic event in apatient; and pacing the heart of the patient before, during, or afterthe ischemic event in a manner such that the pacing pulses are deliveredat a rate substantially higher than the patient's intrinsic heart ratewithout being synchronized to the patient's intrinsic cardiaccontractions.